The check engine light on a 1994 Ford Explorer is an indication that a potential problem exists within the engine management computer. The check engine light refers to all purely electrical or electro-mechanical systems. It does not reflect any purely mechanical problems. When the engine management computer senses an abnormal, out-of-range signal from a sensor, or abnormality in the function of a electro-mechanical device such as a fuel injector, it will set a code in its memory. It will be a sequence of five digits (a letter followed by four numbers.) A code scanner is necessary to extract the codes. A code sheet comes with the scanner so you can decipher the code(s). The only way to clear a check engine light is to correct the problem first.
Instructions
- 1
Locate the OBD (on board diagnostics) port below the dash to the left of the steering column. Plug the code scanner into the OBD port. Turn the ignition key to the "On" position without starting the engine. The warning lights on the dash will illuminate.
2Press the key marked Read on the scanner. Record the code or codes displayed. Turn the key off. Cross-reference the code with the code sheet that accompanies the scanner.
3Repair the associated problem. Of all the codes, the O2 (oxygen sensor) is the most difficult to diagnose. The Ford Explorer has two sensors one in the exhaust system in front of the converter identified as S1 (sensor-1) and one behind the converter identified as S2 (sensor-2). If either sensor displays a code stating heater inoperative it is most likely the sensor or a wire connector to it. If sensor-1 states that the stoic fuel ratio of 14.1 has been exceeded, it is an ambiguous code more commonly referred to as a soft code. It is possible that the sensor has failed; however, in all probability, the mixture is indeed out of parameters. This can be caused by any of the engine electrical components or the engine itself. These possibilities must be explored first. The sensor behind the converter checks the operation of the converter. The signal should be higher than the one in front of the converter indicating that there is less free oxygen coming out than going in. If the signal is the same as the number-1 sensor, the converter has failed.
4Once you have completed the necessary repairs, turn the ignition key to the "On" position without starting the engine. Press the key marked Erase to erase the codes in the computer and extinguish the light until a future problem presents its ugly head.
